Pyrite Surface Alteration of Synthetic Single Crystals as Effect of Microbial Activity and Crystallographic Orientation

To enhance our understanding of effects of microbially mediated pyrite dissolution and the influence parameters such as varied metabolism and crystallographic orientation of pyrite surfaces some dissolution experiments were performed. Microbial etching experiments on pyrite surfaces of different orientation, including {111} and {210} were devised. The experiments were performed using two strains of thermophilic Archaea (Sulfolobus metallicus, Metallosphaera sedula). Epifluorescence microscopy observations showed that the strains attach to the mineral surface. Studies with Scanning Electron Microscopy (SEM) showed cell attachment and etching effects after one week of incubation. Surface alteration produced structures following crystallographic orientation up to several 10 μm in size. For all incubated pyrite samples it became apparent that surface alteration was more pronounced with M. sedula than with S. metallicus.